The present invention relates to improvements in methods of and in apparatus for making tobacco rods. More particularly, the invention relates to improvements in methods of and in apparatus for making one or more continuous rod-like bodies, called fillers, which can be converted into tobacco-containing parts of plain or filter cigarettes, cigars, cigarillos or analogous smokers"" products.
It is well known to make the rod-like filler of a cigarette by showering particles of tobacco (such as shreds of tobacco leaf laminae) which is supplied by a so-called distributor or hopper onto the exposed side of a running sieve-like endless foraminous belt while the other side of the belt travels along the open side of a stationary suction chamber. This results in conversion of the shower into a stream which contains a surplus of tobacco particles and moves lengthwise with the belt past a trimming or equalizing device which removes the surplus. The resulting rod-like filler is confined in a running continuous web of cigarette paper or other suitable wrapping material to form therewith a continuous rod which is severed at regular intervals to yield a succession of plain cigarettes of unit length or multiple unit length. Such products are ready to be confined in packs or to be provided with filter mouthpieces to form therewith filter cigarettes of unit length or multiple unit length. The making of plain or filter cigarillos, cartridges, cigars or analogous smokers"" products involves or can involve procedures or steps similar to those involving the making of plain or filter cigarettes. Conventional machines for the making of plain and filter cigarettes are disclosed, for example, in U.S. Pat. No. 4,281,670 granted Aug. 4, 1981 to Heitmann et al. for xe2x80x9cAPPARATUS FOR INCREASING THE PERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS"" PRODUCTSxe2x80x9d.
It is also known to segregate particles of tobacco dust or analogous less desirable fragments of smokable material from the much more desirable elongated shreds of tobacco leaf laminae and/or from the atmosphere in a cigarette making plant. The thus segregated particles can be utilized for the making of sheets or films of reconstituted tobacco. Alternatively, such less desirable particles of dust or the like can be introduced into the tobacco stream which is borne by the foraminous belt; such introduction takes place prior to removal of the surplus, i.e., prior to conversion of the tobacco stream into a rod-like filler. The purpose of such introduction of tobacco dust and/or like particulate material into the tobacco stream is to contribute to the weight, bulk, density, xe2x80x9cfeelxe2x80x9d and/or other desirable characteristics of smokers"" products embodying lengths of the filler. It is normally preferred to remove all or practically all particles of tobacco dust from the shower or showers of tobacco particles (normally shreds) which are being conveyed to the stream-forming station.
It is equally known to evacuate from the aforementioned suction chamber of a cigarette rod making machine all or practically all particles of tobacco dust. The term xe2x80x9cdustxe2x80x9d is intended to embrace all such particles of tobacco and/or foreign matter entrained by full-sized tobacco shreds which do or can consist of a smokable material but are often too small to allow for appropriate interlacing with genuine tobacco shreds. The thus gathered particles of tobacco dust, as well as relatively small or very small shreds, are admitted into the tobacco stream.
It is further known to simultaneously produce a plurality of (particularly two) continuous cigarette rods each of which yields a series of plain cigarettes of unit length. Reference may be had, for example, to commonly owned U.S. Pat. No. 5,125,419 granted on Jun. 30, 1992 to Heitmann for xe2x80x9cMETHOD OF AND APPARATUS FOR MAKING PLURAL TOBACCO STREAMSxe2x80x9d. Such arrangement multiplies the output of the cigarette making machine with two or more foraminous tobacco rod making conveyors.
As a rule, the aforementioned suction chamber is adjacent that side of an endless foraminous belt or the like which is disposed opposite the side serving to gather a stream of tobacco shreds. The suction chamber is apt to accumulate substantial quantities of tobacco dust within a relatively short interval of time. Such dust normally contains very small particles of tobacco leaves which normally adhere to the adjacent tobacco shreds on their way to the rod forming station but become separated from the shreds during the next-following processing of cigarettes of unit length or multiple unit length. The dust in the plenum chamber further contains minute particles of sand and/or rock as well as relatively small tobacco fragments which are more likely to be interlaced with desirable tobacco shreds of standard size and/or shape and which are less likely to readily penetrate through the openings of the endless foraminous belt.
The relatively small tobacco fragments develop in part during the making of tobacco shreds and in part during transport of shreds from the shredding station to the rod forming station, particularly during transport toward the foraminous belt. Some of the small fragments even penetrate into the openings of the foraminous belt and gather in the suction chamber. Additional relatively small tobacco fragments develop during transport of satisfactory shreds with the foraminous belt; thus, the end portions of a certain percentage of shreds penetrate into the openings of the belt to be sheared off the major portions of the respective tobacco shreds during separation of the respective portions of the tobacco stream from the foraminous belt.
In accordance with heretofore known procedures, all solid particles which happen to penetrate into the suction chamber are evacuated from the chamber with the air stream which enters the chamber by way of openings in the foraminous belt, which flows through the chamber, and which is evacuated by way of one or more outlets. The thus evacuated air is caused to flow into a central dedusting station of the entire cigarette making plant and the thus accumulated mass of dust and minute or relatively small tobacco shreds is thereupon converted into sheets or other configurations of reconstituted tobacco. Such procedure must be carried out by resorting to bulky and costly machinery and is expensive in spite of the fact that the reconstituted tobacco can be or is being reused for the making of smokers"" products. For example, the sheet can be shredded and the thus obtained shreds are admixed to the shreds of the shower (i.e., to the shreds which are obtained as a result of comminution of tobacco leaf laminae).
U.S. Pat. No. 3,282,270 (granted Nov. 1, 1966 to Morris et al. for xe2x80x9cTOBACCO-MANIPULATING APPARATUSxe2x80x9d) discloses a method which involves segregation of tobacco dust directly at the cigarette rod making machine and immediate pneumatic reintroduction of separated dust into the shower of tobacco shreds advancing toward the foraminous belt of the pneumatic conveyor which converts the shower into a continuous tobacco stream. The introduction of dust into the shower is to be carried out by the shreds which constitute the shower, and retention of dust in the stream is to be effected by those shreds which already adhere to the exposed side of the foraminous belt.
A drawback of the just described patented proposal of Morris et al. is that only the relatively large particles of dust are intercepted by tobacco shreds at the foraminous belt. All or nearly all small particles of tobacco dust, sand and other foreign matter are free to reenter the suction chamber so that the air stream issuing from the suction chamber contains a continuously increasing percentage of dust and foreign matter. It is to be borne in mind that the shower of tobacco shreds contains and delivers to the tobacco stream forming station additional particles of tobacco dust, sand and other minute particulate material and that, sooner or later, all or nearly all such particles enter and circulate with the air stream which delivers the solid contents of the suction chamber to the shower of tobacco shreds advancing toward the foraminous belt.
An object of this invention is to provide a method which renders it possible to overcome the drawbacks of heretofore known proposals to remove tobacco dust and other undesirable particles from the mass of comminuted tobacco which is to be converted into one or more rod-like fillers in a cigarette making machine or the like.
Another object of the present invention is to provide a novel and improved method which renders it possible to recover and reuse acceptable fragments of smokable material which happen to penetrate into the suction chamber(s) of a machine for the making of one or more continuous tobacco-containing rods, such as a cigarette rod making machine.
A further object of the invention is to provide a method which reduces the likelihood or prevents the accumulation of large quantities of tobacco dust and like minute particulate material in the suction chamber(s) of a cigarette rod making or an analogous machine for the making of smokers"" products.
An additional object of the instant invention is to provide a novel and improved method of achieving pronounced savings in acceptable smokable material in a machine for converting one or more showers of loose tobacco particles into one or more tobacco streams ready for conversion into rod-like tobacco fillers in a cigarette making or an analogous machine for the mass-production of rod-shaped smokers"" products.
Still another object of the invention is to provide a novel and improved apparatus for the practice of the above outlined method in cigarette rod making and analogous machines.
A further object of the invention is to provide an apparatus which renders it possible to achieve substantial savings in smokable material which is processed in a machine for the making of cigarette rods and the like.
Another object of the invention is to provide an apparatus which can be installed with equal advantage in a machine for the making of a single continuous rod-shaped tobacco filler or for simultaneously turning out a plurality of such rods.
An additional object of the invention is to provide a novel and improved cigarette rod making machine.
Still another object of the invention is to provide a novel and improved arrangement for treating tobacco dust and other small particulate substances gathering in the suction chamber or chambers of a cigarette rod making or an analogous machine.
A further object of the invention is to provide novel and improved smokers"" products wherein the rod-shaped smokable fillers contain tobacco dust in a distribution superior to that in presently known rod-shaped smokers"" products containing recovered tobacco dust and/or smokable particles of similar size.
One feature of our invention resides in the provision of a method of building at least one stream of smokable material from a mixture containing randomly distributed relatively large first particulate material (such as standard-size shreds of tobacco leaf laminae) and randomly distributed relatively small second particulate material including a coarser or larger fraction and a finer or smaller fraction. The coarser fraction can contain or consist of fragments of standard tobacco shreds (such fragments develop in the tobacco shredding machine and/or during travel of standard-size shreds from the shredding machine into the distributor or hopper of a cigarette maker and/or during transport from the hopper to the stream building station). The finer fraction can contain tobacco dust and/or minute fragments of tobacco shreds and/or foreign matter (e.g., small particles of sand, fragments of metal and/or the like).
The improved method comprises a plurality of steps including the step of advancing the mixture against one side of at least one moving belt or band forming part of a pneumatic conveyor and having a permeability such that the at least one belt intercepts and entrains the first material but permits at least some of the second material to pass therethrough. The belt preferably constitutes an endless belt having an elongated lower reach or stretch the underside of which is the aforementioned one side and the upper side of which is adjacent the open underside of a suction chamber which forms part of the pneumatic conveyor and attracts successive increments of the mixture (such mixture can constitute an ascending shower or column of randomly intermixed first and second particulate materials) and causes the first particulate material to adhere to the underside of and to advance with the lower reach of the endless belt while permitting at least some of the second particulate material to penetrate through the lower reach and to enter the suction chamber. The method further comprises the steps of at least partially segregating the coarser and finer fractions of the at least some second material from each other (such step follows the first step as well as the evacuation of the at least some second material from the suction chamber), and of admitting at least some of the thus segregated coarser fraction into the entrained first material at the one side of the at least one belt.
The finer fraction (or that part of the finer fraction) which has passed through the belt for the second time is or can be conveyed (e.g., in an air stream or another suitable carrier medium) from the plenum chamber and is separated from the carrier medium, e.g., in the central dust collecting plant of a cigarette making factory. This ensures that the thus recovered finer fraction cannot enter the atmosphere in the plant and can be put to use, e.g., for the making of sheets or films of reconstituted tobacco.
The at least one belt of the pneumatic conveyor is caused to move lengthwise in a predetermined direction, e.g., past a station at which the surplus of entrained first material is removed by a suitable trimming or equalizing device so that the remaining part of the mass of first material constitutes a continuous rod-like filler ready to be draped into a web of cigarette paper or other suitable wrapping or draping material. The advancing step of the improved method preferably includes feeding the mixture against the one side of the at least one belt in the form of a shower (especially an ascending shower) which is elongated in the predetermined direction so that the first material which is directed against and is intercepted by the one side of the belt forms an elongated tobacco stream which is ready to be trimmed and to be thus converted into a rod-like filler.
The segregating step can include directing at least some second material against the one side of the at least one moving belt.
Alternatively or in addition to the just discussed segregating step, the latter can comprise (or further comprise) directing the at least some second material (i.e., the second material which has already passed through the at least one belt) against the first material which is being entrained by the at least one belt. Otherwise stated, the admitting step can include pneumatically conveying at least some of the segregated coarser fraction into the entrained first material.
The advancing step of the improved method can include advancing the mixture against a relatively large first portion of the one side of the at least one belt, and the segregating step of such method can include directing the at least some second material against a relatively small portion of the one side of the at least one belt so that the finer fraction passes through the at least one belt and at least some of the coarser fraction moves with the at least one belt, and evacuating the finer fraction at the other side of the at least one belt. Such evacuating step can include entraining the finer fraction in an air stream and the improved method can further comprise the step of regulating the quantity of air forming the air stream to establish at the other side of the at least one belt a constant subatmospheric pressure. As already mentioned above, the belt is arranged to move in a predetermined direction (such as past the trimming or equalizing station), and the at least some second material is preferably directed against the one side of such belt upstream of the locus or loci of delivery of first material.
The segregating step of the improved method can include directing the at least some second material into the mixture advancing against the one side of the at least one moving belt. Such method can further comprise the step of converting the entrained first material into a rod-like filler, and such converting step can include removing a first portion (namely the surplus) of the entrained first material from a second portion at the one side of the at least one moving belt; the directing step preferably includes admitting the at least some second material into the second portion of the advancing first material, namely, into the portion which, upon completion of the trimming or equalizing operation, constitutes the rod-like filler.
The improved method can further comprise the step of imparting to the at least some of the segregated second faction a component of movement in the direction of lengthwise movement of the mixture-receiving portion or reach of the belt; the segregated second fraction is preferably imparted such movement prior to the admitting step.
The improved method can be resorted to for simultaneously building at least two streams of smokable material. Such method can further include the step of breaking up the mixture into at least two flows, and the advancing step then includes simultaneously advancing each of the at least two flows against one side of one of at least two discrete moving belts. Still further, such method comprises the step of dividing the at least some second material, which has passed through the respective one of the at least two belts, into at least two masses prior to the segregating step. The just described embodiment of the improved method can further comprise the step of introducing each of the at least two masses into a different one of the at least two streams.
Another feature of the present invention resides in the provision of an apparatus for building at least one stream of smokable material from a mixture containing randomly distributed relatively large first particulate material (such as standard-size shreds of tobacco leaf laminae) and relatively small second particulate material (such as tobacco dust, small or very small portions of tobacco shreds, particles of sand and the like). The improved apparatus comprises at least one pneumatic conveyor having an endless running belt (including a first side and a second side) and at least one first suction chamber adjacent one side of the belt and having an outlet, and the apparatus further comprises means for feeding at least a portion of the mixture against the other side of the belt opposite the first suction chamber. The belt has a permeability such that it entrains the first material but permits at least some second material to pass into the first suction chamber. The improved apparatus also comprises means for evacuating second material from the first suction chamber by way of the aforementioned outlet, means for admitting the evacuated second material against the other side of the belt and/or against the first material being entrained by the belt, at least one second suction chamber disposed at the one side of the belt and serving to gather second material being furnished by the admitting means and having passed through the belt due to suction in the at least one second chamber, and means for drawing air and second material from the at least one second chamber.
The material admitting means and/or the means for drawing second material from the at least one second suction chamber can comprise one or more air conveying pipes, hoses and/or analogous conduits.
The volume of the at least one first suction chamber can greatly exceed the volume of the at least one second suction chamber.
The at least one pneumatic conveyor further includes means (such as one or more driven pulleys) for moving the belt in a predetermined direction, and the at least one second suction chamber can be provided or installed upstream of the at least one first suction chamber (as seen in the predetermined direction). Alternatively, the at least one second suction chamber can be provided in the at least one first suction chamber. The length of the at least one first suction chamber can exceed (e.g., it can be several times) the length of the at least one second suction chamber, as seen in the predetermined direction. Furthermore, the at least one second suction chamber can be spaced apart from the material admitting means, again as seen in the predetermined direction.
It is also possible to construct and install the means for admitting the evacuated second material in such a way that it discharges second material into the feeding means.
The means for admitting the evacuated second material can be arranged to discharge second material with a component of movement in the predetermined direction.
The apparatus can further comprise signal generating sensors and/or other suitable means for monitoring the pressure in the at least one first and/or in the at least one second suction chamber and/or means for regulating the pressure in the at least one first suction chamber. The regulating means can include control means for processing signals being furnished by the aforementioned sensor means and means for adjusting (when warranted) the air drawing means in response to the processed signals.
If the improved apparatus is utilized in a machine for simultaneously producing two or more rod-like fillers of smokable material, the transporting means includes at least two conveyors (each having an endless foraminous belt) and at least one second suction chamber for each conveyor. The feeding means of such apparatus includes means for dividing the mixture into several fractions, one for each conveyor, and means for feeding a discrete fraction of the mixture against the other side of the belt of each conveyor. The means for admitting evacuated second maerial then includes means for directing second material toward the other side of the respective belt at least substantially opposite the respective second suction chamber so that at least a substantial part of the second material having been discharged against the other side of the respective belt is drawn into the respective second suction chamber. In such apparatus, the means for admitting the evacuated second material against the other side of the respective belt and/or against the first material being entrained by the respective belt further includes adjustable means for breaking up second material into discrete masses, one for each of the directing means.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and the modes of installing and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.